I thought I would copy down some notes I've sent out to people who've expressed interest in the C3G about where we're at in terms of membership right now and what types of actions might pique the interest of established members.
Please see the text of a recent response to such a query below:

Always appreciate the interest in what we're doing. We at the C3G right now have the luxury of having a pretty established core group and being a bit picky about who we let have power when it comes to things like initiating designs and voting on the direction of the project.
That doesn't mean that everyone outside looking in has to stay that way - it merely means that if you want to be on the inside looking out, you have to make a case for yourself, not just by asking, but by pitching in and being active and basically working to make yourself indispensable to the project.
There are a few ways to get your "foot in the door," but the best one is hopping on playtesting (when it's available - we're kind of "in-between" playtesting right now). Proofreading, editing, offering general comments about the direction of the project (comments that are accompanied with suggested or possible paths and that show a knowledge of the current conversation rather than coming from left field will get a lot more traction) are all possible avenues to getting involved as well. Honestly, someone who wants to establish himself as a C3G Sidekick or Hero should be prepared to do all of these.
Playtesting alone can get you a badge as an "Ally" which is the first step to getting a position like a Sidekick in the future. But once you're an Ally, you'll need to work to distinguish yourself from the other Allies. Part of this means establishing yourself as a designer as well as a tester/commenter. This means starting your own thread to display your custom card creations and ideas, showing an ability to collaborate with the community, and getting involved with community projects like NM24. Basically, show you have custom making chops, the ability to work well with others, and a general enthusiasm and knowledge for customization in general, and we'll know what we're getting when someone suggests moving you to Sidekick status or something like that.

Anyway, those are just a few notes. Basically the best way to become a C3G member is not to ask for it, but to show you want it. Also, if you are an Ally and you want to gain the ability to design for C3G, go to this LINK to learn more about how you can become part of the design process.

DISCLAIMER: C3G claims no ownership of the characters or artwork used for C3G customs. All rights for the characters belong to their respective publishers/creators. C3G cards are not intended for sale, and C3G does not authorize any party to profit from C3G cards.

He came to our threads and hasn't once asked for a single thing, but instead, he has proven himself over and over that he is willing to work well and diligent on our projects and tasks at hand. He started his own custom project, playtested our work, and comments on just about every aspect of what we are working on. Beyond that, his input is insightful and productive. SirG never sits on his thumbs and waits for an assignment. He is always looking for some way to contribute, which lately, has been proof reading all of our X-Men powers. Furthermore, SirG understands how C3G functions, and he has taken the time to educate himself on our rules, goals, and general way of doing things.

I think SirG is a model Ally, and is a shoe in for soon-to-be Sidekick. If anyone is looking for an example on how to be a good C3G contributor, I think SirG is the cream of the crop.

I agree completely. I love the initiative Sir G. has shown and the steps he's taken to try to prove himself as a creator as well as a contributor since he's wandered into this section of the forums!
After we get into wave one of ala cart, if someone nominates him for sidekick, that will have my full support.

DISCLAIMER: C3G claims no ownership of the characters or artwork used for C3G customs. All rights for the characters belong to their respective publishers/creators. C3G cards are not intended for sale, and C3G does not authorize any party to profit from C3G cards.

I want to take a minute and recognize all the fantastic contributions SirGalahad, Master Tang, Confred, Velenne, Adam Sauza and Quozl have been making to the Ala Cart design process. They give great insightful points and many of them playtested Rise of the Mutants. I would be proud to call any of them fellow Sidekicks. Thanks for the help, guys!

I agree they've all been awesome in Ala Carte. For a few of them, I really loved how they pitched in during the X-Men release as well and I'm holding off on proposing they move to Sidekick until I see whether they're going to contribute at quite the same level as they did there.
For others, I love what they have to say in Ala Carte, but I kind of want to see what they're able to do as custom designers in their own threads before giving them the keys to the kingdom. I'm not sure all of those guys have their own custom threads yet.
Oh, on another note, for Heroes and Sidekicks only, I've started a new Wave to discuss future things if you're interested in such things. But don't say you haven't been invited into the inner circle on this one, because that's what I'm doing.

DISCLAIMER: C3G claims no ownership of the characters or artwork used for C3G customs. All rights for the characters belong to their respective publishers/creators. C3G cards are not intended for sale, and C3G does not authorize any party to profit from C3G cards.

DISCLAIMER: C3G claims no ownership of the characters or artwork used for C3G customs. All rights for the characters belong to their respective publishers/creators. C3G cards are not intended for sale, and C3G does not authorize any party to profit from C3G cards.

Baby step to the playtest... baby step to the art work... baby step to the front page... baby step to the pos rep... baby step to the figure pics... baby step to the personal designs... baby step to the A la Carte... baby step to the suggestions... baby step to the Sidekick/Hero status... Next we work on "untying the knots" of your custom.

DISCLAIMER: C3G claims no ownership of the characters or artwork used for C3G customs. All rights for the characters belong to their respective publishers/creators. C3G cards are not intended for sale, and C3G does not authorize any party to profit from C3G cards.

DISCLAIMER: C3G claims no ownership of the characters or artwork used for C3G customs. All rights for the characters belong to their respective publishers/creators. C3G cards are not intended for sale, and C3G does not authorize any party to profit from C3G cards.